Basic Maple plotting problem not workin

[congraduation]

any how, i have this equation. I have read a quick online tutorial on maple.

this is my equation in raw form

Br*(arctan(W*L/(2*x*(4*x^2+W^2+L^2)^(1/2)))-arctan(W*L/((2*(x+2*T))*[4*(x+2*T)^2+W^2+L^2]^(1/2))))/Pi

because i have 5 varibales, i did

B1(Br,W,L,T,x):= [the above function]

Now, i now have to subsitude the above equation with values, consider the first for varibale to be constant , so i typed in the following command and pressed enter

B1(1.4, 0.1e-1, 0.6e-1, 0.35e-1, x)

and this is what i get, kinda the same way I wanted it to be, simply, a new equation where I'm left with one variable

(1.4*(arctan(0.3000000000e-3/(x*sqrt(4*x^2+0.37e-2)))-arctan(0.6e-3/((2*x+.140)*sqrt([4*(x+0.70e-1)^2+0.37e-2])))))/Pi

but this is where the junk start. I want to plot it so simply running plot[(above eqation),x=50..100) DOESN'T WORK!

plot((1.4*(arctan(0.3000000000e-3/(x*sqrt(4*x^2+0.37e-2)))-arctan(0.6e-3/((2*x+.140)*sqrt([4*(x+0.70e-1)^2+0.37e-2])))))/Pi, x = 50 .. 100)

result:

Error, invalid input: sqrt expects its 1st argument, x, to be of type algebraic, but received [4*(x+0.70e-1)^2+0.37e-2]i don't understand what I'm doning is worng!

another thing,, the answer it calucates is just so wrong if i do it manual like after running this

B1(1.4, 0.1e-1, 0.6e-1, 0.35e-1, 100)

i get

(1.4*(1.499999931*10^(-8)-arctan(0.2997901469e-5/sqrt([40056.02330]))))/Pi

to simply it.. i copy it and paste it in a new line and get this error
Error, invalid input: sqrt expects its 1st argument, x, to be of type algebraic, but received [40056.02330]

the number in brackets is just so wrong then what i caculate by hand

on maple 14

 

[congraduation]

anyone?